let sum4: (x: number, y: number) => number;

type PlusType = (x: number, y: number) => number;
let sum5: PlusType;
const res5 = sum5(1, 2);

type StringNumberSwitch = string | number;
type Direction = "left" | "right" | "up" | "down";

type user = {
  id: number;
  name: string;
  age: number;
} & PlusType;

interface IName {
  name: string;
}
type IPerson1 = IName & {
  age: number;
};
